Hypovitaminosis D in adults with inflammatory bowel disease: potential role of ethnicity.

Background: Although vitamin D deficiency occurs in inflammatory bowel disease (IBD), it is currently unclear to what extent ethnicity affects vitamin D levels. Our aim was therefore to determine the ethnic variation in serum 25-hydroxyvitamin D status and its association with disease severity in adults with IBD.

Methods: We conducted a prospective cohort study in ambulatory care IBD patients. Clinical disease severity was assessed through validated questionnaires. Serum 25-hydroxyvitamin D levels were used for vitamin D status. C-reactive protein (CRP), ferritin and hemoglobin (Hgb) levels were correlated with serum 25-hydroxyvitamin D levels.

Results: Sixty ulcerative colitis (UC) and forty Crohn's disease (CD) patients were enrolled comprising 65 % Caucasians and 29 % South Asians. However, South Asians had consistently lower average serum 25-hydroxyvitamin D levels (All 44.8 ± 18.1 nmol/L, UC 48.2 ± 18.3 nmol/L, CD 24.3 ± 13.3 nmol/L). Hypovitaminosis D was found in 39 % of All, 36.7 % of UC and 42.5 % of CD patients. A significantly higher proportion of South Asians were vitamin D deficient when compared to Caucasians in All and CD groups (58.6 % vs. 30.8 %, p = 0.01 and 85.7 % vs. 32.3 %, p < 0.01, respectively).

Conclusions: A significantly higher percentage of South Asians had hypovitaminosis D when compared to Caucasians. Disease severity trended towards an inverse relationship with vitamin D status in all South Asian and Caucasian CD patients, although most patients in this study had only mild to moderate disease. We suggest that vitamin D supplementation should be considered in all adult IBD patients.